Superabsorbent powders which can absorb many times their weight in liquid often are used in association with incontinent and other absorbent pads such as disposable diapers, bandages and decubitus pads to increase the absorptive capacity of the pads. Typically, these pads have a liquid impervious backing layer and a pervious face layer with an absorbent batt or packet formed from wadding, wood pulp, nonwoven webs of textile fibers or other absorbent material positioned between the backing and face layers. To increase the absorptive capacity of the packet, superabsorbent powder is either interspersed throughout the packet or applied to the packet as a superposed layer thereon. When the packet is wetted, the superabsorbent powder absorbs and retains the liquid.
In the past, many applications of superabsorbent powders in incontinent and other absorbent pads were uneconomical. Superabsorbent powders typically are expensive and their application in an absorbent pad mandate the full efficient use and availability of all the superabsorbent powder so that most of the superabsorbent powder is placed in contact with the liquid being absorbed. Unless the absorptive pad provides sufficient room for expansion or gelling of the powder, the powder is limited in the amount of liquid it can absorb and retain since the powder must have room to expand to absorb liquid.
Many prior pads using superabsorbent powder were limited since liquid flowing through the pad encountered a quantity of powder which expanded, gelled and blocked further fluid flow throughout the pad. Some pads were designed in an attempt to minimize the expanding powder blockage by applying the powder to a corrugated fibrous web such as disclosed in U.S. Pat. No. 4,685,914 to Holtman or by providing for an absorbent packet having capillary flow along webs of textile staple fibers which includes deposits of superabsorbent powder applied thereon such as disclosed in U.S. Pat. No. 4,232,674 to Melican.
However, even with improved pad designs, typically powder migration negates any minimization of powder blockage brought about by the improved designs. For example, in pads having respective liquid impervious and pervious back and face layers, powder migrating from convoluted webs or from absorbent packets often collects between the impervious backing layer and the convoluted webs or absorbent packet contained in the pad. Deposits of migrated powder absorb and retain liquid, expanding and gelling to block further fluid flow between the backing layer and the convoluted webs or absorbent packet. In addition, these pads often suffer other drawbacks. Typically, large grained superabsorbent powder particles are used to prevent vertical powder migration through any webs of textile or other staple fibers. Although a fine grained superabsorbent powder particle would provide a higher surface area per weight of powder, thus increasing the efficiency with which a pad can absorb and retain liquid, many commercially available pads are produced from webs having a web porosity which does not prevent fine grained superabsorbent powder from migrating therethrough.
It is therefore an object of this invention to provide an incontinent pad with an absorbent packet having superabsorbent powder contained therein wherein migration of said superabsorbent powder throughout the pad is limited.
It is another object of this invention to provide an incontinent pad with an absorbent packet having superabsorbent powder contained therein, wherein fluid flow through said pad and packet is not restricted by expanding superabsorbent powder.
It is another object of this invention to provide a high absorbent packet Which can be positioned between the liquid impervious outer surface and a liquid pervious inner surface of an incontinent pad.
It is another object of this invention to provide a high absorbent packet having a superabsorbent powder contained therein wherein vertical and horizontal migration of the powder through the packet is limited or prevented.